Inhibition of the CD47-SIRPα axis for cancer therapy: A systematic review and meta-analysis of emerging clinical data

Phagocytosis-Activating Nanocomplex Orchestrates Macrophage-Mediated Cancer Immunotherapy

The phagocytosis of macrophages to tumor cells represents an alluring strategy for cancer immunotherapy; however, its effectiveness is largely hindered by the detrimental upregulation of anti-phagocytic signals and insufficient expression of pro-phagocytic signals of tumor cells. Here, a pro-phagocytic polymer-based nanocomplex is designed to promote the macrophage engulfment of tumor cells through concurrent modulation of both the "eat me" and "don't eat me" signals. The nanocomplex MNCCD47i-CALRt is formed by complexing a synthetic PAMAM derivative (G4P-C7A) that is capable of intrinsically inducing the exposure of calreticulin (CALR, a crucial pro-phagocytic protein) and a small inference RNA that can inhibit the expression of CD47 (a primary anti-phagocytic protein). MNCCD47i-CALRt can significantly delay tumor growth and prolong the survival of tumor-bearing mice with negligible hematopoietic toxicity in multiple murine colorectal cancer models. Furthermore, the pro-phagocytic capacity of MNCCD47i-CALRt is validated in the patient-derived tumor organoid model. Collectively, the phagocytosis-promoting nanocomplex provides a simple and potent strategy for boosting macrophage-mediated cancer immunotherapy.

Cell membrane nanoparticles in cancer therapy: From basic structure to surface functionalization

Cell membrane nanoparticles (CNPs) have recently garnered significant attention as effective drug-delivery vehicles. Beyond their simple function of encapsulating cargo within a lipid bilayer structure, the cell membrane is a complex entity derived from biological materials, presenting a variety of surface proteins and glycans. Notable features that enhance their effectiveness as delivery vehicles include the inhibition of protein corona formation in the plasma and the suppression of macrophage phagocytosis, both of which contribute to prolonged blood circulation. Furthermore, CNPs exhibit homotypic targeting effects toward their cells of origin, resulting in reduced side effects, and because they are not xenobiotics, the likelihood of nonspecific immune activation is also minimized. This review focuses on various applications of CNPs in cancer therapeutic studies, examining their structural evolution and surface engineering developments. We introduce studies that leverage the inherent functionality of cell membranes and recent research in functional CNPs synthesized through genetic or chemical engineering methods. Through this review, we aim to trace the progression of CNP research, explore potential directions for their use in biomedical applications, and assess the prospects for clinical trials.

Immunogenic Cell Death: the Key to Unlocking the Potential for Combined Radiation and Immunotherapy

Immunogenic cell death (ICD) enhances anti-tumor immunity by releasing tumor-associated antigens and activating the anti-tumor immune system response. However, its potential remains understudied in combination therapies. Here, we develop a mathematical model to quantify the role of ICD in optimizing the efficacy of combined radiotherapy (RT) and macrophage-based immunotherapy. Using preclinical murine data targeting the SIRP α -CD47 checkpoint, we show that RT alone induces minimal ICD, whereas disrupting the SIRP α -CD47 axis significantly enhances both phagocytosis and systemic immune activation. Our model predicts an optimal RT dose (6-8 Gy) for maximizing ICD, a dose-dependent abscopal effect, and a hierarchy of treatment efficacy, with SIRP α -knockout macrophages exhibiting the strongest tumoricidal activity. These findings provide a quantitative framework for designing more effective combination therapies, leveraging ICD to enhance immune checkpoint inhibition and radiotherapy synergy.

AFP shields hepatocellular carcinoma from macrophage phagocytosis by regulating HuR-mediated CD47 translocation in cellular membrane

OBJECTIVES

Alpha fetoprotein(AFP) overexpression connecting with macrophage dysfunction remain poorly defined. In this study, explore AFP regulates macrophage immunomodulation in hepatocellular carcinoma(HCC) through comprehensive in vitro and in vivo studies.

METHODS

Immunohistochemical and immunofluorescence staining was used to analyze the relativity of AFP and cellular membrane CD47 expression in clinical 30 HCC tissues, and the expression of AFP and CD47 in HCC cells. The intelligent living-cell high-throughput imaging analyzer was applied to dynamically track and image of macrophages to phagocytize HCC cells. The effect of AFP on regulating the level of CD47 in cellular membrane and growth of tumor in vivo was performed by animal experiment. The association of AFP and CD47 in HCC cells was detected by single cell analysis.

RESULTS

The present results indicated that AFP upregulated the localization of CD47 on the HCC cell surface. CD47 overexpression stimulates HCC to escape immune surveillance by transmitting "don't eat me" signals to macrophages, lead to inhibit macrophage to phagocytize HCC cells. Mechanistically, the results demonstrated that AFP enhanced CD47 membrane translocation by interacting with Hu-Antigen R(HuR), an RNA-binding protein that regulates mRNA stability and translation. AFP alters the subcellular distribution of HuR, increasing its cytoplasmic accumulation and binding to CD47 transcript.

CONCLUSIONS

AFP enhanced CD47 membrane translocation by interacting with HuR. These findings proved that AFP could inhibit macrophage to phagocytize HCC cells by upregulating the localization of CD47 on the HCC cell surface. Combination of AFP with CD47 blockade may be a potential therapeutic strategy for HCC treatment.

Harnessing the tumor microenvironment: targeted cancer therapies through modulation of epithelial-mesenchymal transition

The tumor microenvironment (TME) is integral to cancer progression, impacting metastasis and treatment response. It consists of diverse cell types, extracellular matrix components, and signaling molecules that interact to promote tumor growth and therapeutic resistance. Elucidating the intricate interactions between cancer cells and the TME is crucial in understanding cancer progression and therapeutic challenges. A critical process induced by TME signaling is the epithelial-mesenchymal transition (EMT), wherein epithelial cells acquire mesenchymal traits, which enhance their motility and invasiveness and promote metastasis and cancer progression. By targeting various components of the TME, novel investigational strategies aim to disrupt the TME's contribution to the EMT, thereby improving treatment efficacy, addressing therapeutic resistance, and offering a nuanced approach to cancer therapy. This review scrutinizes the key players in the TME and the TME's contribution to the EMT, emphasizing avenues to therapeutically disrupt the interactions between the various TME components. Moreover, the article discusses the TME's implications for resistance mechanisms and highlights the current therapeutic strategies toward TME modulation along with potential caveats.

Modulation of Tumor-Associated Macrophages to Overcome Immune Suppression in the Hepatocellular Carcinoma Microenvironment

Hepatocellular carcinoma (HCC) is a major global health issue characterized by poor prognosis and complex tumor biology. One of the critical components of the HCC tumor microenvironment (TME) is tumor-associated macrophages (TAMs), which play a pivotal role in modulating tumor growth, immune evasion, and metastasis. Macrophages are divided into two major subtypes: pro-inflammatory M1 and anti-inflammatory M2, both of which may exist in TME with altered function and proportion. The anti-inflammatory M2 macrophages are further subdivided into four distinct immune suppressive subsets. TAMs are generally counted as M2-like macrophages with altered immune suppressive functions that exert a significant influence on both cancer progression and the ability of tumors to escape immune surveillance. Their involvement in modulating immune responses via different mechanisms at the local and systemic levels has made them a key target for therapeutic interventions seeking to enhance treatment outcomes. How TAMs' depletion influences immune responses in cancer is the primary interest in cancer immunotherapies. The purpose of this review is to delve into the recent progress made in TAM-targeting therapies. We will explore the current theories, benefits, and challenges associated with TAMs' depletion or inhibition. The manuscript concludes with future directions and potential implications for clinical practice.

Translating CD47-targeted therapy in gastrointestinal cancers: Insights from preclinical to clinical studies

This review presents a thorough investigation of the role of CD47 in gastrointestinal cancers. We performed a comprehensive, in-depth review of over 100 preclinical and clinical studies focused on inhibiting CD47. The research highlights the potential of targeted CD47 to enhance existing treatments by boosting the immune response to cancer cells. Considering the essential need to balance the toxicity and efficacy of CD47 inhibition, our review emphasizes the need to optimize CD47 inhibitors. We also demonstrate the necessity of combining CD47 antibodies with conventional chemotherapy, radiotherapy, or other targeted therapies to enhance treatment effectiveness. Finally, we propose the integration of CD47-targeted therapies into treatment plans as a promising approach to reshape the therapeutic landscape of gastrointestinal cancers. Continued research in this field holds great potential for improving the outcomes of gastrointestinal cancer patients and overcoming the challenges associated with this formidable spectrum of diseases.

Clinical landscape of macrophage-reprogramming cancer immunotherapies

Tumour-associated macrophages (TAMs) sustain a tumour-supporting and immunosuppressive milieu and therefore aggravate cancer prognosis. To modify TAM behaviour and unlock their anti-tumoural potential, novel TAM-reprogramming immunotherapies are being developed at an accelerating rate. At the same time, scientific discoveries have highlighted more sophisticated TAM phenotypes with complex biological functions and contradictory prognostic associations. To understand the evolving clinical landscape, we reviewed current and past clinically evaluated TAM-reprogramming cancer therapeutics and summarised almost 200 TAM-reprogramming agents investigated in more than 700 clinical trials. Observable overall trends include a high frequency of overlapping strategies against the same therapeutic targets, development of more complex strategies to improve previously ineffective approaches and reliance on combinatory strategies for efficacy. However, strong anti-tumour efficacy is uncommon, which encourages re-directing efforts on identifying biomarkers for eligible patient populations and comparing similar treatments earlier. Future endeavours will benefit from considering the shortcomings of past treatment strategies and accommodating the emerging complexity of TAM biology.

The CD47/TSP-1 axis: a promising avenue for ovarian cancer treatment and biomarker research

BACKGROUND

Ovarian cancer (OC) remains one of the most challenging and deadly malignancies facing women today. While PARP inhibitors (PARPis) have transformed the treatment landscape for women with advanced OC, many patients will relapse and the PARPi-resistant setting is an area of unmet medical need. Traditional immunotherapies targeting PD-1/PD-L1 have failed to show any benefit in OC. The CD47/TSP-1 axis may be relevant in OC. We aimed to describe changes in CD47 expression with platinum therapy and their relationship with immune features and prognosis.

METHODS

Tumor and blood samples collected from OC patients in the CHIVA trial were assessed for CD47 and TSP-1 before and after neoadjuvant chemotherapy (NACT) and multiplex analysis was used to investigate immune markers. Considering the therapeutic relevance of targeting the CD47/TSP-1 axis, we used the CD47-derived TAX2 peptide to selectively antagonize it in a preclinical model of aggressive ovarian carcinoma.

RESULTS

Significant reductions in CD47 expression were observed post NACT. Tumor patients having the highest CD47 expression profile at baseline showed the greatest CD4+ and CD8+ T-cell influx post NACT and displayed a better prognosis. In addition, TSP-1 plasma levels decreased significantly under NACT, and high TSP-1 was associated with a worse prognosis. We demonstrated that TAX2 exhibited a selective and favorable biodistribution profile in mice, localizing at the tumor sites. Using a relevant peritoneal carcinomatosis model displaying PARPi resistance, we demonstrated that post-olaparib (post-PARPi) administration of TAX2 significantly reduced tumor burden and prolonged survival. Remarkably, TAX2 used sequentially was also able to increase animal survival even under treatment conditions allowing olaparib efficacy.

CONCLUSIONS

Our study thus (1) proposes a CD47-based stratification of patients who may be most likely to benefit from postoperative immunotherapy, and (2) suggests that TAX2 is a potential alternative therapy for patients relapsing on PARP inhibitors.

EGFR Oncogenic Mutations in NSCLC Impair Macrophage Phagocytosis and Mediate Innate Immune Evasion Through Up-Regulation of CD47

INTRODUCTION

EGFR-mutated NSCLC is characterized by an immunosuppressive microenvironment that confers limited clinical effectiveness to anti-PD-1 or PD-L1 antibodies. Despite the discouraging outcomes of immunotherapy, novel immune checkpoints are constantly emerging, among which the specific vulnerability for therapeutic intervention in the context of EGFR-mutated NSCLC remains unresolved.

METHODS

Data sets of patient- and cell line-levels were used for screening and mutual validation of association between EGFR mutation and a panel of immune checkpoint-related genes. Regulatory mechanism was elucidated through in vitro manipulation of EGFR signaling pathway and evaluated by immunoblot analysis, quantitative polymerase chain reaction, flow cytometry, immunofluorescence staining, and chromatin immunoprecipitation. In vivo investigation of different therapeutic strategies were conducted using both immunocompetent and immunodeficient mouse models.

RESULTS

Among all screened immune checkpoints, CD47 emerged as the candidate most relevant to EGFR activation. Mechanistically, EGFR mutation constitutively activated downstream ERK and AKT pathways to respectively up-regulate the transcriptional factors c-Myc and NF-κB, both of which structurally bound to the promotor region of CD47 and actively transcribed this "don't eat me" signal. Impaired macrophage phagocytosis was observed on introduction of EGFR-sensitizing mutations in NSCLC cell line models, whereas CD47 blockade restored the phagocytic capacity and augmented tumor cell killing in both in vitro and in vivo models. Remarkably, the combination of anti-CD47 antibody with EGFR tyrosine kinase inhibitor revealed an additive antitumor activity compared with monotherapy of either antitumor agent in both immunocompetent and adaptive immunity-deficient mouse models.

CONCLUSIONS

EGFR-sensitizing mutation facilitates NSCLC's escape from innate immune attack through up-regulating CD47. Combination therapy incorporating CD47 blockade holds substantial promise for clinical translation in developing more effective therapeutic approaches against EGFR-mutant NSCLC.

Spatial distribution of tumor-resident macrophages as predictive biomarkers in endometrial cancer

BACKGROUND

To investigate the role of CD47 expression and its relationship with tumor-resident macrophages, specifically at the tumor margin, in patients with type II endometrial cancer. This study aims to elucidate whether CD47 could serve as a prognostic marker and to understand the dynamics between CD47 and macrophages, which could inform new therapeutic strategies.

METHODS

A retrospective cohort study was conducted involving 75 patients of type II endometrial. Immunohistochemical analysis was performed to assess CD47 expression and macrophage markers (CD68 and CD163).

RESULTS

The study found no direct correlation between CD47 expression levels and overall survival (p = 0.32), challenging its role as an independent prognostic marker in type II endometrial cancer. The higher expression of CD47 had significantly less incidence of endometrioid carcinoma G3 (p = 0.047). The negative correlation between CD47 H-score and the density of CD68-positive macrophages at tumor margin was statistically significant (p = 0.049). A high density of CD68-positive macrophages at the tumor margin but a low density of CD163-positive macrophages at the tumor margin were associated with poorer prognosis (p = 0.036).

CONCLUSIONS

The complex interaction between CD47 and macrophages, particularly at the tumor margin, suggests new avenues for targeted therapy in type II endometrial cancer.

Efferocytosis by macrophages in physiological and pathological conditions: regulatory pathways and molecular mechanisms

Efferocytosis is defined as the highly effective phagocytic removal of apoptotic cells (ACs) by professional or non-professional phagocytes. Tissue-resident professional phagocytes ("efferocytes"), such as macrophages, have high phagocytic capacity and are crucial to resolve inflammation and aid in homeostasis. Recently, numerous exciting discoveries have revealed divergent (and even diametrically opposite) findings regarding metabolic immune reprogramming associated with efferocytosis by macrophages. In this review, we highlight the key metabolites involved in the three phases of efferocytosis and immune reprogramming of macrophages under physiological and pathological conditions. The next decade is expected to yield further breakthroughs in the regulatory pathways and molecular mechanisms connecting immunological outcomes to metabolic cues as well as avenues for "personalized" therapeutic intervention.

New horizons for platinum-resistant ovarian cancer: insights from the 2023 American Society of Clinical Oncology (ASCO) and European Society for Medical Oncology (ESMO) Annual Meetings

Platinum-resistant ovarian cancer is difficult to treat and has a poor prognosis. Patients with platinum-resistant ovarian cancer have limited treatment options and often have a limited benefit from existing chemotherapeutic agents. There is a lack of contemporary effective anticancer drugs and reliable predictive biomarkers for this aggressive cancer. Recent cutting-edge research presented at the 2023 American Society of Clinical Oncology (ASCO) and the European Society for Medical Oncology (ESMO) Annual Meetings has provided insights into several potential therapeutic targets, such as DNA damage repair proteins, cell-cycle regulators, and immune-modulating agents. In addition, antibody-drug conjugates have provided new practice-changing results in platinum-resistant ovarian cancer. Here, we review the results of research presented at this annual event, with a focus on clinical trials investigating novel treatment approaches for platinum-resistant ovarian cancer, in addition to predictive and prognostic biomarkers for optimal patient selection, and other topics, such as real-world evidence.

Unleashing the power of immune checkpoints: Post-translational modification of novel molecules and clinical applications

Immune checkpoint molecules play a pivotal role in the initiation, regulation, and termination of immune responses. Tumor cells exploit these checkpoints to dampen immune cell function, facilitating immune evasion. Clinical interventions target this mechanism by obstructing the binding of immune checkpoints to their ligands, thereby restoring the anti-tumor capabilities of immune cells. Notably, therapies centered on immune checkpoint inhibitors, particularly PD-1/PD-L1 and CTLA-4 blocking antibodies, have demonstrated significant clinical promise. However, a considerable portion of patients still encounter suboptimal efficacy and develop resistance. Recent years have witnessed an exponential surge in preclinical and clinical trials investigating novel immune checkpoint molecules such as TIM3, LAG3, TIGIT, NKG2D, and CD47, along with their respective ligands. The processes governing immune checkpoint molecules, from their synthesis to transmembrane deployment, interaction with ligands, and eventual degradation, are intricately tied to post-translational modifications. These modifications encompass glycosylation, phosphorylation, ubiquitination, neddylation, SUMOylation, palmitoylation, and ectodomain shedding. This discussion proceeds to provide a concise overview of the structural characteristics of several novel immune checkpoints and their ligands. Additionally, it outlines the regulatory mechanisms governed by post-translational modifications, offering insights into their potential clinical applications in immune checkpoint blockade.

Immune pathway through endometriosis to ovarian cancer

Endometriosis is an estrogen-dependent inflammatory disease, defined by the presence of functional endometrial tissue outside of the uterine cavity. This disease is one of the main gynecological diseases, affecting around 10%-15% women and girls of reproductive age, being a common gynecologic disorder. Although endometriosis is a benign disease, it shares several characteristics with invasive cancer. Studies support that it has been linked with an increased chance of developing endometrial ovarian cancer, representing an earlier stage of neoplastic processes. This is particularly true for women with clear cell carcinoma, low-grade serous carcinoma and endometrioid. However, the carcinogenic pathways between both pathologies remain poorly understood. Current studies suggest a connection between endometriosis and endometriosis-associated ovarian cancers (EAOCs) via pathways associated with oxidative stress, inflammation, and hyperestrogenism. This article aims to review current data on the molecular events linked to the development of EAOCs from endometriosis, specifically focusing on the complex relationship between the immune response to endometriosis and cancer, including the molecular mechanisms and their ramifications. Examining recent developments in immunotherapy and their potential to boost the effectiveness of future treatments.

Difference between Keratinized- and Non-Keratinized-Originating Epithelium in the Process of Immune Escape of Oral Squamous Cell Carcinoma

Immune checkpoint inhibitors (ICIs), including anti-programmed cell death 1 ligand 1 (PD-L1) antibodies, are significantly changing treatment strategies for human malignant diseases, including oral cancer. Cancer cells usually escape from the immune system and acquire proliferative capacity and invasive/metastatic potential. We have focused on the two immune checkpoints, PD-1/PD-L1 and CD47/SIRPα, in the tumor microenvironment of oral squamous cell carcinoma (OSCC), performed a retrospective analysis of the expression of seven immune-related factors (PD-L1, PD-1, CD4, CD8, CD47, CD56 and CD11c), and examined their correlation with clinicopathological status. As a result, there were no significant findings relating to seven immune-related factors and several clinicopathological statuses. However, the immune checkpoint-related factors (PD-1, PD-L1, CD47) were highly expressed in non-keratinized epithelium-originated tumors when compared to those in keratinized epithelium-originated tumors. It is of interest that immunoediting via immune checkpoint-related factors was facilitated in non-keratinized sites. Several researchers reported that the keratinization of oral mucosal epithelia affected the immune response, but our present finding is the first study to show a difference in tumor immunity in the originating epithelium of OSCC, keratinized or non-keratinized. Tumor immunity, an immune escape status of OSCC, might be different in the originating epithelium, keratinized or non-keratinized.

Effects of a humanized CD47 antibody and recombinant SIRPα proteins on triple negative breast carcinoma stem cells

Signal regulatory protein-α (SIRPα, SHPS-1, CD172a) expressed on myeloid cells transmits inhibitory signals when it engages its counter-receptor CD47 on an adjacent cell. Elevated CD47 expression on some cancer cells thereby serves as an innate immune checkpoint that limits phagocytic clearance of tumor cells by macrophages and antigen presentation to T cells. Antibodies and recombinant SIRPα constructs that block the CD47-SIRPα interaction on macrophages exhibit anti-tumor activities in mouse models and are in ongoing clinical trials for treating several human cancers. Based on prior evidence that engaging SIRPα can also alter CD47 signaling in some nonmalignant cells, we compared direct effects of recombinant SIRPα-Fc and a humanized CD47 antibody that inhibits CD47-SIRPα interaction (CC-90002) on CD47 signaling in cancer stem cells derived from the MDA-MB- 231 triple-negative breast carcinoma cell line. Treatment with SIRPα-Fc significantly increased the formation of mammospheres by breast cancer stem cells as compared to CC-90002 treatment or controls. Furthermore, SIRPα-Fc treatment upregulated mRNA and protein expression of ALDH1 and altered the expression of genes involved in epithelial/mesenchymal transition pathways that are associated with a poor prognosis and enhanced metastatic activity. This indicates that SIRPα-Fc has CD47-mediated agonist activities in breast cancer stem cells affecting proliferation and metastasis pathways that differ from those of CC-90002. This SIRPα-induced CD47 signaling in breast carcinoma cells may limit the efficacy of SIRPα decoy therapeutics intended to stimulate innate antitumor immune responses.

Hypercholesterolemia exacerbates in-stent restenosis in rabbits: Studies of the mitigating effect of stent surface modification with a CD47-derived peptide

BACKGROUND AND AIMS

Hypercholesterolemia (HC) has previously been shown to augment the restenotic response in animal models and humans. However, the mechanistic aspects of in-stent restenosis (ISR) on a hypercholesterolemic background, including potential augmentation of systemic and local inflammation precipitated by HC, are not completely understood. CD47 is a transmembrane protein known to abort crucial inflammatory pathways. Our studies have examined the interrelation between HC, inflammation, and ISR and investigated the therapeutic potential of stents coated with a CD47-derived peptide (pepCD47) in the hypercholesterolemic rabbit model.

METHODS

PepCD47 was immobilized on metal foils and stents using polybisphosphonate coordination chemistry and pyridyldithio/thiol conjugation. Cytokine expression in buffy coat-derived cells cultured over bare metal (BM) and pepCD47-derivatized foils demonstrated an M2/M1 macrophage shift with pepCD47 coating. HC and normocholesterolemic (NC) rabbit cohorts underwent bilateral implantation of BM and pepCD47 stents (HC) or BM stents only (NC) in the iliac location.

RESULTS

A 40 % inhibition of cell attachment to pepCD47-modified compared to BM surfaces was observed. HC increased neointimal growth at 4 weeks post BM stenting. These untoward outcomes were mitigated in hypercholesterolemic rabbits treated with pepCD47-derivatized stents. Compared to NC animals, inflammatory cytokine immunopositivity and macrophage infiltration of peri-strut areas increased in HC animals and were attenuated in HC rabbits treated with pepCD47 stents.

CONCLUSIONS

Augmented inflammatory responses underlie severe ISR morphology in hypercholesterolemic rabbits. Blockage of initial platelet and leukocyte attachment to stent struts through CD47 functionalization of stents mitigates the pro-restenotic effects of hypercholesterolemia.

Peroxisome Proliferator-Activated Receptor agonists and antagonists: an updated patent review (2020-2023)

INTRODUCTION

The search for novel compounds targeting Peroxisome Proliferator-Activated Receptors (PPARs) is currently ongoing, starting from the previous successfully identification of selective, dual or pan agonists. In last years, researchers' efforts are mainly paid to the discovery of PPARγ and δ modulators, both agonists and antagonists, selective or with a dual-multitarget profile. Some of these compounds are currently under clinical trials for the treatment of primary biliary cirrhosis, nonalcoholic fatty liver disease, hepatic, and renal diseases.

AREAS COVERED

A critical analysis of patents deposited in the range 2020-2023 was carried out. The novel compounds discovered were classified as selective PPAR modulators, dual and multitarget PPAR agonists. The use of PPAR ligands in combination with other drugs was also discussed, together with novel therapeutic indications proposed for them.

EXPERT OPINION

From the analysis of the patent literature, the current emerging landscape sees the necessity to obtain PPAR multitarget compounds, with a balanced potency on three subtypes and the ability to modulate different targets. This multitarget action holds great promise as a novel approach to complex disorders, as metabolic, inflammatory diseases, and cancer. The utility of PPAR ligands in the immunotherapy field also opens an innovative scenario, that could deserve further applications.

α5-nAChR/STAT3/CD47 axis contributed to nicotine-related lung adenocarcinoma progression and immune escape

OBJECTIVES

The CHRNΑ5 gene, which encodes the α5-nicotinic acetylcholine receptor (α5-nAChR), is related to lung cancer and nicotine addiction. Smoking is closely related to the immunosuppressive effect of macrophages. CD47, a phagocytosis checkpoint in macrophages, is a therapeutic target in various cancer types. Nevertheless, the relationship between α5-nAChR and CD47 in lung cancer is still unclear.

METHODS AND RESULTS

The present study showed that α5-nAChR-mediated CD47 expression via STAT3 signaling, consequently leading to tumor progression and immune suppression in lung adenocarcinoma (LUAD). α5-nAChR expression was correlated with STAT3 expression, CD47 expression, smoking status and poor prognosis of LUAD in vivo. In vitro, α5-nAChR expression mediated the phosphorylation of STAT3, and phosphorylated STAT3 bound to the CD47 promoter and mediated CD47 expression. Downregulation of α5-nAChR and/or CD47 significantly reduced cell proliferation, migration, invasion, stemness and IL-10 expression, but increased TNF-α expression and phagocytosis of macrophages in LUAD. Furthermore, α5-nAChR/CD47 signaling contributed to the growth of subcutaneous xenograft tumors and liver metastasis of tumors in mice.

CONCLUSION

The α5-nAChR/STAT3/CD47 axis contributed to the progression and immune escape of lung cancer and may be a potential target for LUAD immunotherapy.

Tumor Immune Cell Targeting Chimeras (TICTACs) For Targeted Depletion of Macrophage-Associated Checkpoint Receptors

Immune cells in the tumor microenvironment are not only powerful regulators of immunosuppression and tumorigenesis, but also represent a dominant cell type, with tumor-associated macrophages (TAMs) comprising up to 50% of total cell mass in solid tumors. Immunotherapies such as immune checkpoint inhibitors (ICIs) derive their efficacy from this cancer-immune cell interface, however, immune-related adverse events resulting from systemic blockade remain a significant challenge. To address this need for potent, yet highly tumor-specific immunotherapies, we developed Tumor-Immune Cell Targeting Chimeras (TICTACs), antibody conjugates that are capable of selectively depleting immune checkpoint receptors such as SIRPa from the surface of TAMs. These chimeric molecules consist of a synthetic glycan ligand that binds the C-type lectin CD206, a well-established TAM marker, conjugated to a non-blocking antibody that binds but does not inhibit the checkpoint receptor. By engaging CD206, which constitutively recycles between the plasma membrane and early endosomes, TICTACs facilitate robust removal of the checkpoint receptors from the surface of CD206high macrophages, while having no effect on CD206low macrophages. By decoupling antibody selectivity from its blocking function, we present a new paradigm for developing highly tumor-specific immunotherapies.

CD47 masks pro-phagocytic ligands in cis on tumor cells to suppress antitumor immunity

Cancer cells often overexpress CD47, which triggers the inhibitory receptor SIRPα expressed on macrophages, to elude phagocytosis and antitumor immunity. Pharmacological blockade of CD47 or SIRPα is showing promise as anticancer therapy, although CD47 blockade has been associated with hematological toxicities that may reflect its broad expression pattern on normal cells. Here we found that, in addition to triggering SIRPα, CD47 suppressed phagocytosis by a SIRPα-independent mechanism. This mechanism prevented phagocytosis initiated by the pro-phagocytic ligand, SLAMF7, on tumor cells, due to a cis interaction between CD47 and SLAMF7. The CD47-SLAMF7 interaction was disrupted by CD47 blockade and by a first-in-class agonist SLAMF7 antibody, but not by SIRPα blockade, thereby promoting antitumor immunity. Hence, CD47 suppresses phagocytosis not only by engaging SIRPα, but also by masking cell-intrinsic pro-phagocytic ligands on tumor cells and knowledge of this mechanism may influence the decision between CD47 blockade or SIRPα blockade for therapeutic purposes.

CD47: The Next Frontier in Immune Checkpoint Blockade for Non-Small Cell Lung Cancer

The success of PD-1/PD-L1-targeted therapy in lung cancer has resulted in great enthusiasm for additional immunotherapies in development to elicit similar survival benefits, particularly in patients who do not respond to or are ineligible for PD-1 blockade. CD47 is an immunosuppressive molecule that binds SIRPα on antigen-presenting cells to regulate an innate immune checkpoint that blocks phagocytosis and subsequent activation of adaptive tumor immunity. In lung cancer, CD47 expression is associated with poor survival and tumors with EGFR mutations, which do not typically respond to PD-1 blockade. Given its prognostic relevance, its role in facilitating immune escape, and the number of agents currently in clinical development, CD47 blockade represents a promising next-generation immunotherapy for lung cancer. In this review, we briefly summarize how tumors disrupt the cancer immunity cycle to facilitate immune evasion and their exploitation of immune checkpoints like the CD47-SIRPα axis. We also discuss approved immune checkpoint inhibitors and strategies for targeting CD47 that are currently being investigated. Finally, we review the literature supporting CD47 as a promising immunotherapeutic target in lung cancer and offer our perspective on key obstacles that must be overcome to establish CD47 blockade as the next standard of care for lung cancer therapy.